should i invest 2100 or buy another one

Always a really difficult question to answer. Since you just put new tires on it, it seems like you have already invested prior to the $2,100. So, if you have a pretty good assurance that the $2,100 can buy you a fair amount of time driving the car (meaning the rest of the vehicle is sound and without any signs of issues), and you have always been good and current on scheduled maintenance -- then it may be a good idea to keep this car. If there is any doubt, then you could end up putting good money after bad. It's going to be a matter of weighing personal pros and cons regarding your transportation needs, budget, history with this vehicle and anticipated future needs.

Along with the above advice, it would be a good idea to have the entire vehicle thoroughly inspected and service history looked at by a trusted service provider. To be done properly there will be a charge but is well worth any small charge this entails before spending additional money on a vehicle. Especially if it turns up any future potential issues.